1. ATM 401/501 Status of Forecasting: Spring 2013 1. Forecasting at NCEP Environmental Modeling Center http://www.emc.ncep.noaa.gov/ Ocean Prediction Center http://www.opc.ncep.noaa.gov/ National Hurricane Center http://www.nhc.noaa.gov/ Hydrometeorological Prediction Center http://www.hpc.ncep.noaa.gov/ Link to HPC verification page Storm Prediction Center http://www.spc.noaa.gov/

2. Motivation Flooding is a leading cause of weather-related deaths "Improvements in QPF and mesoscale rainfall prediction need to be a top NWS research and training priority." 2009 SE US Flood Service Assessment Atlanta: Sept. 21, 2009 Nashville: May 1, 2010Cedar Rapids: June 2008

3. Bias: The basic formula for computing the bias is Forecast / Observed This quantity gauges the accuracy of areal/station coverage of a specified precipitation threshold amount, regardless of accuracy in location. An ideal forecast would have Forecast = Observed to yield a Bias of 1. Threat Score (TS): The formula for computing the TS is Correct / (Forecast + Observed - Correct) For a perfect forecast, Correct = Forecast = Observed to yield a TS of 1. The worst possible forecast, with Correct = 0, yields a TS of zero. Threat and Bias Scores

9. Extreme Events are Challenging Forecast improvement of extreme events (4”) lags improvement of more common events (1”)

24. Tennessee Example 12 UTC 1 May – 12 UTC 3 May ObservedHPC Deterministic (Issued 12 UTC 1 May)

25. 12 UTC 1 May – 12 UTC 3 May Observed95th percentile Tennessee Example